Celestron AstroMaster 114AZ Instruction Manual page 22

With Polaris or a bright star centered within the field of view, focus with either t With Polaris or a bright star centered within the field of view, focus with either t
h h ighest power ocular, i.e. the shortest focal length in mm, such as a 6mm or 4mm. Another option is to use ighest power ocular, i.e. the shortest focal length in mm, such as a 6mm or 4mm. Another option is to use
a longer focal length ocular with a Barlow lens. When a star is in focus it should look like a sharp pinpoint a longer focal length ocular with a Barlow lens. When a star is in focus it should look like a sharp pinpoint
of light. If, when focusing on the star, it is irregular in shape or appears to have a flare of light at its edge, of light. If, when focusing on the star, it is irregular in shape or appears to have a flare of light at its edge,
this means your mirrors aren't in alignment. If you notice the appearance of a flare of light from the star this means your mirrors aren't in alignment. If you notice the appearance of a flare of light from the star
that remains stable in location, just as you go in and out of exact focus, then re-collimation will help that remains stable in location, just as you go in and out of exact focus, then re-collimation will help
sharpen the image. sharpen the image.
When satisfied with When satisfied with the collimation, tighten the small locking screws the collimation, tighten the small locking screws
Fig 7-2 Even though the star pattern appears the same on both sides of focus, they are asymmetric. The dark
obstruction is skewed off to the left side of the diffraction pattern indicating poor collimation.
T T ake note of the direction the light appears to flare. For example, if it appears to flare toward the three ake note of the direction the light appears to flare. For example, if it appears to flare toward the three
o o 'clock position in the field of view, then you must move whichever screw or combination of collimation 'clock position in the field of view, then you must move whichever screw or combination of collimation
sc sc rews necessary to move the star's image toward the direction of the flaring. In this example, you would rews necessary to move the star's image toward the direction of the flaring. In this example, you would
w w ant to move the image of the star in your eyepiece, by adjusting the collimation screws, toward the three ant to move the image of the star in your eyepiece, by adjusting the collimation screws, toward the three
o' o' clock position in the field of view. It may only be necessary to adjust a screw enough to move the star's clock position in the field of view. It may only be necessary to adjust a screw enough to move the star's
im im age from the center of the field of view to about halfway, or less, toward the field's edge (when using a age from the center of the field of view to about halfway, or less, toward the field's edge (when using a
h h igh power ocular). igh power ocular).
C C ollimation adjustments are best made while viewing the star's position in the field of ollimation adjustments are best made while viewing the star's position in the field of
v v iew and turning the adjustment screws simultaneously. This way, you can see exactly iew and turning the adjustment screws simultaneously. This way, you can see exactly
w w hich way the movement occurs. It may be helpful to have two people working hich way the movement occurs. It may be helpful to have two people working
toget toget her: one viewing and instructing which screws to turn and by how much, and the her: one viewing and instructing which screws to turn and by how much, and the
other performing the adjustments. other performing the adjustments.
IMPORTANT: After making the first, or each adjustment, it is necessary to re-aim the IMPORTANT: After making the first, or each adjustment, it is necessary to re-aim the
telescope tube to re-center the star again in the center of the field of view. The star image telescope tube to re-center the star again in the center of the field of view. The star image
can then be judged for symmetry by going just inside and outside of exact focus and can then be judged for symmetry by going just inside and outside of exact focus and
noting the star's pattern. Improvement should be seen if the proper adjustments are noting the star's pattern. Improvement should be seen if the proper adjustments are
made. Since three sc made. Since three sc rews are present, it may be necessary to move at least two rews are present, it may be necessary to move at least two
to to achieve the necessary mirror movement. achieve the necessary mirror movement.
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he standard ocular or your he standard ocular or your
Figure 7-3
A collimated tele
should appear as a
symmetrical ring pattern
similar to the diffraction similar to the diffraction
disk seen here. disk seen here.
scope